JD 450 Winch Problem. Need help

[DLE55]

Hello, I have a 450C with an older 450 winch on it. The winch hasn't worked since I got it. I am trying to get the winch going. I have 450
service manual that has this winch in it. It's a 3325 with the older spool-valve control. You check the pressure on the outside of the housing cover that covers the brake. Should be 1000 psi @ 1900 rpm. Here's the problem.
When I release the brake (free spool) I get 0 psi and brake does not release. When I wind in the drum, I get 600 psi and then it fades down to 0 psi. The brake area is dry and brake cylinder not leaking. Do I need to look for trouble in the control valve or the pump area first? I have the service manual but I'm not sure where to start.

Thanks for any help.
David Edwards

[digitup2]

Look into fluid condition then level then change the filter first .Digitup.

[DLE55]

I changed the oil and oil filter first. It did look really bad. Someone on another website said it may be the pump screen. I guess I'll check the pump and screen. Maybe that's all it is.
Thanks,